Geographic Photographer Critically Injured in Africa

National Geographic photographer Bobby Model remains in critical condition at a South African hospital after a chunk of concrete smashed through the windshield of a pickup truck and hit him in the head Thursday.

Model, 34, is in the intensive care unit at the Vergelegen Medi-Clinic in Cape Town.

The Kenya-based U.S. native was on vacation when the melon-size piece of concrete struck his pickup truck, which his sister Faith was driving. She was not hurt.

An email update today from Model's family and friends at the hospital said that "his condition has deteriorated."

"The contusion appears to have spread and is putting pressure on his brain stem. He is not in any pain, and his vitals are being kept stable. He has not regained consciousness."

Stone Throwing

Police are still investigating whether the chunk of concrete was purposely thrown at Model's car or fell off a truck, according to the Cape Argus news agency.

Model (pronounced moe-DELL) and his sister were struck near the Monwabisi resort, which is close to Khayelitsha, one of Cape Town's sprawling poor townships.

The region has become notorious for stone-throwing attacks in recent years. A man was killed last year when a brick was hurled through his windshield, Britain's Guardian Unlimited news site reported Sunday.

Emerging Explorer

In 2006 the National Geographic Society named Model an "emerging explorer," a program that recognizes and supports "dynamic personalities who are making a significant contribution to world knowledge through exploration."

(National Geographic News is part of the National Geographic Society.)